I've only completed the normal arena. I'm not good enough for vet and I only have access to templates.

I've done it with magicka templar and sorc and stamina nightblade. If I were to use a scale of 0-100 to compare the difficulty between them (not difficulty of the arena) where lower is easier. Templar would be a 1, Sorc a 10 and Nightblade a 100. It is FAR harder with a Stam NB.

Templar was easier than Sorc, even with shield stacking. Puncturing Sweeps out heals most incoming damage.

As for vet, I couldn't be the first level with any of them. Everything hit so hard and many times I went from full health to dead in less than a second. After a dozen or so tries I gave up for now. Will see if it's more doable with my real characters with proper gear.